NAME
sigtimedwait,
sigwaitinfo, sigwait
— wait for queued
signals
LIBRARY
library “libc”
SYNOPSIS
#include
<signal.h>
int
sigtimedwait(const
sigset_t * restrict set,
siginfo_t * restrict
info, const struct
timespec * restrict timeout);
int
sigwaitinfo(const
sigset_t * restrict set,
siginfo_t * restrict
info);
int
sigwait(const
sigset_t * restrict set,
int * restrict sig);
DESCRIPTION
sigwaitinfo()
and
sigwait()
return the first pending signal from the set specified by
set. Should multiple signals from
set be pending, the lowest numbered one is returned. The
selection order between realtime and non-realtime signals is unspecified. If
there is no signal from set pending at the time of the
call, the calling thread is suspended until one of the specified signals is
generated.
sigtimedwait()
is exactly equal to sigwaitinfo(), except
timeout specifies the maximum time interval for which
the calling thread will be suspended. If timeout is
zero (tv_sec == tv_nsec == 0), sigtimedwait() only
checks the currently pending signals and returns immediately. If
NULL is used for timeout,
sigtimedwait() behaves exactly like
sigwaitinfo() in all regards.
If several threads are waiting for a given signal, exactly one of them returns from the signal wait when the signal is generated.
Behaviour of these functions is unspecified if any of the signals in set are unblocked at the time these functions are called.
RETURN VALUES
Upon successful completion of
sigtimedwait() or
sigwaitinfo() info is updated
with signal information, and the function returns the signal number.
Otherwise, -1 is returned and the global variable
errno indicates the error. Upon successful completion
of sigwait() sig is updated
with the signal number, and the function returns 0. Otherwise, a non-zero
error code is returned.
ERRORS
sigwaitinfo() and
sigwait() always succeed.
sigtimedwait() will fail and the
info pointer will remain unchanged if:
- [
EAGAIN] - No signal specified in set was generated in the specified timeout.
sigtimedwait() may also fail if:
- [
EINVAL] - The specified timeout was invalid.
This error is only checked if no signal from set is pending and it would be necessary to wait.
SEE ALSO
STANDARDS
The functions sigtimedwait(),
sigwaitinfo(), and sigwait()
conform to IEEE Std 1003.1-2001
(“POSIX.1”).
HISTORY
The sigtimedwait(),
sigwaitinfo(), and sigwait()
functions appeared in NetBSD 2.0.